There is a growing awareness of the importance of the man-machine interface. The issues range from the mundaneness of simply wanting to have "an intuitive interface" on a consumer item for the purposes of "ease-of-use," to the opposite extreme of life-and-death issues surrounding the accidental misoperation of a control knob in a nuclear power plant, airplane, or automobile.
This invention deals specifically with thumbwheels: radial knobs with the axis of rotation parallel with and submerged from an exposed surface. Thumbwheels offer the advantages of a compact size and a clean appearance without protrusions which can catch accidentally on passing objects.
However, the existing thumbwheels have severe problems with regard to ergonomics. The thumbwheel interface commonly used on many portable CD players as a volume control serves as an ideal example.
Prior to pressing the "play" button, the user must try to remember whether the device was last used at high volume or low volume. If it were last used on a high volume setting, the device may blare loudly at a time when loudness is undesirable. While this problem could be solved with small numbers molded into the material of the knob, designers commonly desire only a fraction of an inch of the thumbwheel edge to protrude, for the reasons offered above. One practical solution to this problem is for the user to arbitrarily lower the volume as a precaution against it starting to play too loudly.
This "solution" highlights the second problem of existing thumbwheel designs: It is difficult for the user to ascertain which direction to turn the knob to achieve a desired goal. Commonly, there is a graphic molded into the plastic case indicating which direction is louder. However, in accordance with the small overall size of the product, this graphic is small and difficult to read. It is additionally difficult to read because the graphic is made of the same material and color as the case, requiring the user to move their head or the device until the graphic becomes identifiable. Furthermore, it is even more difficult to read this information during the common situations of darkness, while driving, exercising etc. This example highlights the problems of all existing thumbwheel interfaces, regardless of application.
What is desirable is a means to provide information about the status of the thumbwheel control to the user, regardless of whether the device is on or off.
It is also desirable to provide directional information to the user in such a way that the information can be conveyed during the adverse conditions in which products are commonly used: while driving, in darkness, while exercising, etc.
Finally, it is desirable to achieve these goals with negligible increase to the manufacturing cost.